Implantable device including a resorbable carrier

ABSTRACT

An implantable device for body tissue, including an electrical subsystem that flexes within and interfaces with body tissue and a carrier that operates in the following two modes: provides structural support for the electrical subsystem during implantation of the device in body tissue and allows flexing of the electrical subsystem after implantation of the device in body tissue. The implantable device is preferably designed to be implanted into the brain, spinal cord, peripheral nerve, muscle, or any other suitable anatomical location. The implantable device, however, may be alternatively used in any suitable environment and for any suitable reason.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/980,659 filed 17 Oct. 2007 and entitled “Carrier for an ImplantableDevice System”, which is hereby incorporated in its entirety by thisreference.

This application is related to US Publication Number 2008/0208283published on 28 Aug. 2008 and entitled “Neural Interface System”, whichissued as U.S. Pat. No. 8,731,673 on 20 May 2014, and which isincorporated in its entirety by this reference.

TECHNICAL FIELD

This invention relates generally to the implantable device field, andmore specifically to an implantable device including a resorbablecarrier.

BACKGROUND

Conventional microfabricated electrode arrays by themselves are oftennot mechanically robust enough to be inserted into body tissue.Therefore, they must be coupled to a carrier that is strong enough toresist buckling while being inserted into the tissue. Conventionalcarriers typically remain implanted with the microfabricated electrodearrays, potentially reducing the ability of the microfabricatedelectrode arrays to move freely in the tissue. Thus, there is a need foran improved carrier that increases the ability of the microfabricatedelectrode arrays to move freely. This invention provides such animproved and useful carrier.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a representation of the device of the preferred embodimentsof the invention, and FIGS. 1B-1D are detailed views of FIG. 1A, showinga connector, a more detailed view of the connector, and a proximal endof the system, respectively.

FIG. 2 is a representation of the device of FIG. 1, shown with twocross-sectional views.

FIG. 3 is a representation of the device of a second version of thepreferred embodiments of the invention, shown in an exploded,pre-assembled view.

FIGS. 4A-C are representations of the method of the preferredembodiments of the invention, shown with the three major steps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of preferred embodiments of the invention isnot intended to limit the invention to these embodiments, but rather toenable any person skilled in the art to make and use this invention.

As shown in FIGS. 1 and 2, the implantable device of the preferredembodiments includes a carrier 10 and an electrical subsystem 12 coupledto the carrier 10. The carrier 10 functions to facilitate the insertionof the electrical subsystem 12 and is adapted to allow the electricalsubsystem 12 to move freely in the tissue. The implantable device ispreferably designed to be implanted into the brain, spinal cord,peripheral nerve, muscle, or any other suitable anatomical location. Theimplantable device, however, may be alternatively used in any suitableenvironment and for any suitable reason.

The carrier 10 functions to facilitate the insertion of the electricalsubsystem 12 and is adapted to allow the electrical subsystem 12 to movefreely in the tissue or other substances. The electrical subsystem 12 ispreferably attached to the carrier 10 such that the carrier functions toprovide structural support. The carrier may include a sharpened endadapted to penetrate the tissue and aid in the insertion of the carrierand electrical subsystems into the tissue. The carrier 10 may alsoinclude alignment and or fixation features to facilitate positioning andstabilizing the electrical subsystem 12 in the tissue.

The carrier 10 of the preferred embodiments is resorbable into tissueafter a period of time. Upon resorption of the carrier 10, theelectrical subsystem 12 supported by the carrier will be left to floatfreely in the brain or other suitable tissue or material. The resorbablecarrier is preferably made of a material that demonstrates at least oneof the following characteristics: minimal foreign body reaction,biocompatibility, biodegradability, long-term mechanical and chemicalstability, sterilizability, and sufficient porosity. The material ispreferably adapted to undergo a controlled action and reaction to thesurrounding tissue, a controlled chemical breakdown and resorption,replacement by regenerating tissue, stimulation of regeneration ofliving tissues, or any combination thereof. The resorbable carrier ispreferably made from a bioresorbable polymer. The bioresorbable polymeris preferably polyglycolide or polylactide, but may alternatively bemade from any suitable bioresorbable material such as a biodegradablemagnesium alloy or a corrodible iron alloy. If the bioresorbable polymeris polyglycolide (or any other material that absorbs into the body afterapproximately one month), the carrier absorbs into the body at about thesame time the body heals around the implanted device, which may beadvantageous in some situations. If the bioresorbable polymer ispolylactide (or any other material that absorbs into the body afterapproximately one year), the carrier absorbs into the body much afterthe body heals around the implanted device, which may be advantageous inother situations.

The carrier 10 may further extend the functionality of the device byproviding fluidic channels through which therapeutic drugs, drugs toinhibit biologic response to the implant, or any other suitable fluid orsubstance may be transmitted. The fluidic channels are preferablychannels defined by the geometry of the carrier 10, but mayalternatively be separate microtubes molded, inserted, woven, knitted,or otherwise disposed into the carrier 10. The channels preferablyprovide for the precise delivery of specific pharmaceutical compounds tolocalized regions of the body, such as the nervous system, and couldfacilitate, for example, intraoperative mapping procedures or long-termtherapeutic implant devices. The fluidic channels may also provide alocation through which a stiffener (or even a shape-memory alloy such asNitinol) may be inserted to aid with the implantation or to facilitatepost-implantation navigation of the device. The shape of the carrier ispreferably tubular with about a 1-mm diameter, but may alternatively besolid or any other suitable shape of any suitable diameter for thedesired functions.

The carrier 10 is preferably made from a material that is woven orknitted, but may alternative be made from a material that is cast,molded, or machined. The carrier 10 is preferably flexible, but mayalternatively be rigid or semi rigid. The material may be uniformlyrigid, or rigid only in a particular direction (such as the axialdirection). The resorbable carrier may also be impregnated with fluidsand/or deliver the fluids such as drugs and/or neurotrophins, similar tothe “Stent Device and Method” of U.S. Pat. No. 7,001,680, which isincorporated in its entirety by this reference. The carrier 10 may befurther adapted to act as a template for tissue regeneration and/or as amatrix for autologous or analogous cells or stem cells.

The carrier 10 may be made from a combination of materials. The layersor portions of distinct materials may have distinct absorption,degradation, or incorporation times. The distinct materials may furtherinclude distinct particles, agents, and/or cells that they deliver orrelease into the tissue. The carrier 10 may further include scaffoldingfor structural support and/or for drug or cell delivery. The scaffoldingis preferably bioresorbable, but may alternatively remain implanted withthe device.

The carrier 10 may be manufactured in one of several variations. In afirst variation, the carrier may be manufactured such that the weave ofthe material is large enough to accept “weaving” of the electricalsubsystem 12 directly into the fabric. In this variation, the electricalsubsystem can be adapted to be woven in and out of the resorbablecarrier to secure the electrical subsystem 12 to the carrier 10. Asingle electrical subsystem 12 could be woven into the fabric ormultiple subsystems could be incorporated, resulting in athree-dimensional system of electrical subsystems. In a secondvariation, the electrical subsystem could be coupled directly to thesurface of the carrier using a biocompatible adhesive such as epoxy orsilicone. In this variation, the weave of the resorbable carrier may betighter and/or the porosity of the carrier may be smaller as theelectrical subsystem 12 is not woven into the material in thisvariation. In a third variation, the resorbable carrier may bemanufactured as a concentric, multi-lumen structure. In this variation,the electrical subsystem 12 may be coupled to the carrier between theinner and outer lumens of the electrical subsystem.

Although the carrier 10 is preferably one of these several variations,of several various materials, manufactured in several variations, thecarrier may be any suitable element, material, manufactured in anysuitable fashion to facilitate the insertion of the electrical subsystem12 and to allow the electrical subsystem 12 to move freely in the tissueor other substances.

The electrical subsystem 12 of the preferred embodiments functions tointerface with the tissue, or any other suitable substance, within whichit has been implanted. The electrical subsystem 12 may include multipledifferent electrical subsystems or a plurality of the same subsystems.The electrical subsystem 12 is preferably at least one of severalversions or any combination thereof.

The electrical subsystem 12 is preferably a neural interface electrodearray. The electrode array preferably has a plurality of electrodesites, and more preferably both stimulation sites 20 and recording sites22. The neural interface electrode array is adapted to provide dynamictunable electrical stimulation ranging from stimulation with macroscalespecificity to microscale directional, patterning. The electrode arrayis preferably adapted to optimally sample (record) and/or selectivelyactivate (stimulate) neural populations. The plurality of electrodesites can be tuned for recording, stimulation, or any combinationthereof. Additionally, at least two electrode sites may be grouped toform a larger composite site that enables tuning the neural interfaceregion for recording and/or stimulation.

The neural interface electrode array is preferably made from a thin-filmpolymer substrate, such as parylene or some combination of parylene andinorganic dielectrics, but may alternatively be made out of any suitablematerial including, for example, silicon. The neural interface electrodearray is preferably made such that there is high density of electrodesites at a first end of the array (the distal end) and bonding regionsat a second end of the array (the proximal end). The distal end of thearray is preferably coupled to the carrier 10 to provide structuralsupport. The electrode array may further include fluidic channelsproviding the capability to deliver therapeutic drugs, drugs to inhibitbiologic response to the implant, or any other suitable fluid.

The neural interface electrode array in this variation is preferably acomposite assembly that includes the neural interface electrode arrayand the carrier 10. The neural interface electrode array includes twopieces, a distal element and a proximal element. The distal elementwraps or is woven around the circumference of the carrier 10. Ascendingfrom the distal element, are preferably interconnects that transitionfrom the outer surface of the carrier 10 into a single connector 14,such that the entire proximal element is imbedded in silicone. Tofacilitate adhesion between the carrier 10 and the neural interfaceelectrode array, small non-homogeneous perforations are preferablymicromachined in the neural interface electrode array to allow for thematerial of the carrier 10 to form a robust anchor with the electrodearray.

In a second version of the preferred embodiments, as shown in FIG. 3,the neural interface electrode array preferably defines series of“cut-aways” or perforations 18 that axially extend in a discontinuousmanner along the length of the neural interface electrode array. Withthe perforations, the neural interface electrode array preferably hasadequate flexibility to allow bending and flowing of the device withinbody tissue after implantation of the device. The perforations 18preferably extend in a radial direction completely through the neuralinterface electrode array, and preferably extend in a circumferentialdirection approximately 45-90 degrees. The neural interface electrodearray preferably includes two perforation series, and thus the neuralinterface electrode array preferably extends 180-270 degrees in theareas with perforations. The perforation series is preferablydiscontinuous (i.e., the neural interface electrode array extendscompletely in the circumferential direction at particular points alongthe length of the neural interface electrode array). While the neuralinterface electrode array has been described as having perforations, itis also possible for the neural interface electrode array to bedescribed as being one or more strips that are circumferentiallyconnected by several “bridges”.

In a third version of the preferred embodiments, the neural interfaceelectrode array omits the “bridges” and is merely one or morerectangular and generally planar (i.e., either flat or slightly curved)“strips”. The carrier provides structural support for these “strips” tobe placed onto a stylet and implanted into body tissue. Although theelectrical subsystem 12 is preferably one of these three versions, theelectrical subsystem 12 may be any suitable element or combination ofelements to perform the desired functions.

The device of the preferred embodiments may further include anadditional electrical subsystem that functions to operate with theelectrical subsystem 12. The additional electrical subsystem may includemultiple different electrical subsystems or a plurality of the samesubsystems. The additional electrical subsystem is preferably at leastone of several versions or any combination thereof. In a first version,the additional electrical subsystem is a suitable electronic subsystemto operate with an implantable neural interface. The additionalelectrical subsystem may be a printed circuit board with or withouton-board integrated circuits and/or on-chip circuitry for signalconditioning and/or stimulus generation, an Application SpecificIntegrated Circuit (ASIC), a multiplexer chip, a buffer amplifier, anelectronics interface, an implantable pulse generator, an implantablerechargeable battery, integrated electronics for either real-time signalprocessing of the input (recorded) or output (stimulation) signals,integrated electronics for control of the fluidic components, any othersuitable electrical subsystem, or any combination thereof. Although theadditional electrical subsystem is preferably one of these severalsubsystems, the additional electrical subsystem may be any suitableelement or combination of elements to operate any suitable electricalsubsystem 12.

The device of the preferred embodiments may further include a connector14 that functions to couple the electrical subsystem 12 to theadditional electrical subsystem. The connector 14 is preferably one ofseveral versions. As shown in FIGS. 1 and 2, the cable is preferably aflexible ribbon cable. The ribbon cable is preferably polymer ribboncable, but may alternatively be any other suitable ribbon cable. Theconnector 14 may alternatively be any suitable element to couple theelectrical subsystem 12 to the additional electrical subsystem, such aswires, conductive interconnects, etc. The ribbon cable may be encased insilicone or any other suitable material. In some versions, theelectrical subsystem may have multiple ribbon cables. Preferably,multiple ribbon cables would be physically attached along their entirelength, using a suitable adhesive such as medical grade adhesive or anyother suitable connection mechanism. The cable is preferably connectedto the electrical subsystems through ball bonds or any other suitableconnection mechanisms. The connector 14 may alternatively be seamlesslymanufactured with the first and or additional electrical subsystem. Theconnector 14 may further include fluidic channels adapted to delivertherapeutic drugs, drugs to inhibit biologic response to the implant, orany other suitable fluid.

As shown in FIG. 3, the device of the preferred embodiments may furtherinclude a stylet 16. The stylet 16 of the preferred embodimentsfunctions to penetrate the tissue or other material and/or functions toprovide structural support to the device during implantation of thedevice. The stylet 16 is preferably inserted into a lumen of the carrier10, but may alternatively be located and inserted into any suitablecomponent of the device in any suitable manner. The stylet 16 mayinclude a sharpened end adapted to penetrate the tissue and aid in theinsertion of the stylet, the carrier 10, and/or the electricalsubsystems into the tissue. The stylet 16 is preferably removed from thetissue following the placement of an electrical subsystem, but mayalternatively be adapted to remain in the tissue while still allowingthe implanted electrical subsystem 12 to float freely in the brain. Thismay be accomplished by the stylet being selectively flexible (throughelectrical stimulus or other suitable method) or by being resorbableinto the tissue after a period of time. The stylet 16 is preferably madefrom a stiff material such as metal, but may alternatively be made fromany suitable material. In one variation, the metal is an insulated metalwire. In this variation, the insulated metal wire may not haveinsulation covering a sharpened tip, and thus can be used as aconventional single-channel microelectrode.

As shown in FIG. 4, a method of implanting and using the implantabledevice and its corresponding electrical components preferably includesthe following steps: (a) providing an electrical subsystem and a carrierthat provides structural support for the electrical subsystem; (b)implanting the electrical subsystem and the carrier into the bodytissue; and (c) dissolving the carrier into the body tissue and allowingthe electrical subsystem to flex within and interface with the bodytissue. Step (c) may include dissolving the carrier into the body tissueat a rate approximately equal to the healing process of the body tissue,or may include dissolving the carrier into the body tissue at a ratemuch slower than the healing process of the body tissue. The method mayalso include providing a stylet, placing the electrical subsystem andthe carrier onto the stylet, and penetrating the body tissue with thestylet.

Although omitted for conciseness, the preferred embodiments includeevery combination and permutation of the various carriers 10, thevarious electrical subsystems, the various connectors, the variousstylets, and the various methods of use.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaim.

I claim:
 1. An implantable electrode device, comprising: a) a carrierextending along a first carrier length from a proximal carrier portionto a distal carrier portion having a distal carrier end; b) a firstelectrical subsystem, comprising: i) at least one electrode site; ii) anelectrode substrate supporting the at least one electrode site, whereinat least a portion of the electrode substrate supporting the at leastone electrode site is woven with the carrier so that the at least oneelectrode site has an exposed surface facing outwardly from theelectrode substrate opposite the carrier; and iii) an electricalconnector extending from the at least one electrode site to a proximalconnector portion adjacent to the proximal carrier portion; and c)wherein the carrier is of a bioresorbable material that is absorbableinto body tissue after implantation of the electrode device comprisingthe carrier and the first electrical subsystem, thereby leaving the atleast one electrode site facing outwardly toward the body tissue fromthe supporting electrode substrate.
 2. The implantable electrode deviceof claim 1, wherein the first electrical subsystem is flexible afterabsorption of the carrier into body tissue.
 3. The implantable electrodedevice of claim 1 wherein the bioresorbable material of the carrier isselected from the group consisting of polyglycolide, polylactide, amagnesium alloy, and a corrodible iron alloy.
 4. The implantableelectrode device of claim 1, wherein the carrier has a tubular shape. 5.The implantable electrode device of claim 4 wherein there are aplurality of electrode sites supported by the electrode substrate andwherein the electrode substrate is woven with the tubular carrier sothat the plurality of electrode sites extend both circumferentially andaxially relative to the first carrier length.
 6. The implantableelectrode device of claim 4 wherein the tubular carrier has a diameterof about one millimeter.
 7. The implantable electrode device of claim 1wherein the carrier has a woven structure.
 8. The implantable electrodedevice of claim 1, wherein the at least one electrode site of the firstelectrical subsystem is configured to interface with neural tissue. 9.The implantable electrode device of claim 8, wherein the firstelectrical subsystem includes a plurality of electrode sites that areconfigured to electrically stimulate different portions of neuraltissue.
 10. The implantable electrode device of claim 1 wherein thereare a plurality of electrode sites supported by the electrode substrateand wherein the electrode substrate is woven with the carrier so thatthe plurality of electrode sites extend both circumferentially andaxially relative to the first carrier length.
 11. The implantableelectrode device of claim 1 wherein there are a plurality of electrodesites supported by the electrode substrate, and wherein the plurality ofelectrode sites are configured to electrically record different portionsof neural tissue.
 12. The implantable electrode device of claim 1wherein the electrode substrate is of a thin-film polymer.
 13. Theimplantable electrode device of claim 12, wherein the thin-film polymeris selected from the group consisting of parylene and silicone.
 14. Theimplantable electrode device of claim 1, wherein the electrode substratehas a tubular shape.
 15. The implantable electrode device of claim 1wherein the electrode substrate has a series of perforations thataxially extend in a discontinuous manner along a second electrodesubstrate length.
 16. The implantable electrode device of claim 1wherein the electrode substrate is a thin-film substrate.
 17. Theimplantable electrode device of claim 1 wherein the first electricalsubsystem has an elongated, substantially planar shape.
 18. Theimplantable electrode device of claim 1 wherein the proximal connectorportion of the first electrical subsystem is electrically connectable toa second electrical subsystem that is configured to control the at leastone electrode site.
 19. The implantable electrode device of claim 1wherein the electrical connector is a flexible ribbon cable.
 20. Theimplantable electrode device of claim 1 wherein a lumen extends throughthe carrier along the first carrier length from the proximal carrierportion to the distal carrier end.
 21. The implantable electrode deviceof claim 20 wherein the lumen is configured to receive a stylet having asharpened end adapted to extend outwardly from the distal carrier end.22. The implantable electrode device of claim 1 wherein the electrodesubstrate includes longitudinal and circumferential bridge strips, andwherein one or more longitudinal bridge strip is connected by thecircumferential bridge strips, thereby defining a series ofdiscontinuous perforations in the electrode substrate of the firstelectrical subsystem.
 23. The implantable electrode device of claim 1wherein the carrier comprises an inner tubular sidewall disposed insidean outer tubular sidewall with the first electrical subsystem locatedbetween the inner and outer carrier sidewalls, but with the exposedsurface of the at least one electrode site facing outwardly from theelectrode substrate opposite the inner and outer carrier sidewalls. 24.The implantable electrode device of claim 1 wherein the bioresorhablematerial of the carrier is completely absorbable into body tissue withinabout one month after implantation of the electrode device.
 25. Theimplantable electrode device of claim 1 wherein the bioresorhablematerial of the carrier is completely absorbable into body tissue withinabout one year after implantation of the electrode device.
 26. Theimplantable electrode device of claim 1 wherein the first electricalsubsystem defines a perforation, and wherein the carrier is anchorablein body tissue in the perforation.
 27. An implantable electrode device,comprising: a) a carrier extending along a first carrier length from aproximal carrier portion to a distal carrier portion; b) an electricalsubsystem, comprising: i) a plurality of electrode sites; ii) anelectrode substrate supporting the plurality of electrode sites, whereinat least a portion of the electrode substrate supporting the pluralityof electrode sites is woven with the carrier so that the electrode sitesare both circumferentially and axially disposed relative to the firstcarrier length and wherein the plurality of electrode sites haverespective exposed surfaces facing outwardly from the electrodesubstrate opposite the carrier; and iii) an electrical connectorextending from each of the plurality of electrode sites to a proximalconnector portion adjacent to the proximal carrier portion; and c)wherein the carrier is of a bioresorbable polymer selected from thegroup consisting of polyglycolide, polylactide, a magnesium alloy, and acorrodible iron alloy and that is absorbable into body tissue afterimplantation of the electrode device comprising the carrier and theelectrical subsystem, thereby leaving the plurality of electrode sitesfacing outwardly toward the body tissue from the supporting electrodesubstrate.
 28. The implantable electrode device of claim 27 wherein thecarrier has a tubular shape.
 29. The implantable electrode device ofclaim 27 wherein a lumen extends through the carrier along the firstcarrier length from the proximal carrier portion to a distal carrier endof the distal carrier portion.
 30. The implantable electrode device ofclaim 27 wherein the electrode substrate has a tubular shape.
 31. Theimplantable electrode device of claim 27 wherein the electrode substrateis substantially planar.
 32. An implantable electrode device,comprising: a) a carrier, comprising: i) a woven carrier sidewallextending along a first carrier length from a proximal carrier portionto a distal carrier portion having a distal carrier end; and ii) a lumenextending through the carrier along the first carrier length from theproximal carrier portion to the distal carrier end; b) an electricalsubsystem, comprising: i) at least one electrode site; ii) an electrodesubstrate supporting the electrode site, wherein at least a portion ofthe electrode substrate supporting the at least one electrode site isinterwoven with the carrier sidewall so that the at least one electrodesite has an exposed electrode surface facing outwardly, away from theelectrode substrate interwoven with the carrier; and iii) an electricalconnector extending from the at least one electrode site to a proximalconnector portion adjacent to the proximal carrier portion; and c)wherein the carrier sidewall is of a bioresorbable polymer that isabsorbable into body tissue after implantation of the electrode devicecomprising the carrier interwoven with the electrode substrate, therebyleaving the at least one electrode site facing outwardly, away from thesupporting electrode substrate.
 33. The implantable electrode device ofclaim 32 wherein the carrier sidewall has a tubular shape.
 34. Theimplantable electrode device of claim 32 wherein the electrode substratehas a tubular shape.
 35. The implantable electrode device of claim 32wherein the electrical subsystem has an elongated, substantially planarshape.
 36. An implantable electrode device, comprising: a) a carriercomprising a carrier sidewall extending along a carrier length from aproximal carrier portion to a distal carrier portion having a distalcarrier end; b) an electrical subsystem, comprising: i) a plurality ofelectrode sites; ii) an electrode substrate supporting the plurality ofelectrode sites, wherein the electrode substrate is supported by thecarrier with the plurality of electrode sites extending bothcircumferentially and axially relative to the carrier length and whereinthe electrode sites each have an exposed surface facing outwardly fromthe electrode substrate opposite the carrier; and iii) an electricalconnector extending from each of the plurality of electrode sites to aproximal connector portion adjacent to the proximal carrier portion; andc) wherein the carrier is of a bioresorbable material that is absorbableinto body tissue after implantation of the electrode device comprisingthe carrier and the electrical subsystem, thereby leaving the pluralityelectrode sites facing outwardly toward the body tissue from thesupporting electrode substrate.
 37. The implantable electrode device ofclaim 36, wherein the electrode substrate has a tubular shape.
 38. Animplantable electrode device, comprising: a) a carrier, comprising: i) acarrier sidewall extending along a carrier length from a proximalcarrier portion to a distal carrier portion having a distal carrier end;and ii) a lumen extending through the carrier along the carrier lengthfrom the proximal carrier portion to the distal carrier end; b) anelectrical subsystem, comprising: i) at least one electrode site; ii) anelectrode substrate supporting the at least one electrode site, whereinat least a portion of the electrode substrate supporting the at leastone electrode site is supported by the carrier so that the at least oneelectrode site has an exposed surface facing outwardly from theelectrode substrate opposite the carrier; and iii) an electricalconnector extending from the at least one electrode site to a proximalconnector portion adjacent to the proximal carrier portion; and c)wherein the carrier is of a bioresorbable material that is absorbableinto body tissue after implantation of the electrode device comprisingthe carrier and the electrical subsystem, thereby leaving the at leastone electrode site facing outwardly toward the body tissue from thesupporting electrode substrate.
 39. The implantable electrode device ofclaim 38 wherein the carrier sidewall has a substantially tubular shape.